Setting Up KVM Virtualization

KVM virtualization is included in the 2.6 Linux kernel, so all recent distributions support it without the need to install a custom kernel. However, it depends on the CPU supporting either the Intel VT or AMD-V virtualization extensions in order to run virtual systems at a reasonable speed.

On some systems, these extensions are disabled in the BIOS by default. Enabling them requires booting the system from the console, entering the BIOS menu and finding the option to turn on virtualization extensions. In some cases the system must then be fully shut down and started up again for this change to take effect.

Also, the host system should have LVM setup and have plenty of free space in its volume group, so that Cloudmin can create VM disk images as logical volumes.

For KVM instances to access the host system's network, you must setup a network bridge. These instructions assume that your host system has only one network interface, and it is eth0 .

Setting up a Host System Running Webmin

If your host system is running Webmin 1.554 or later, the network bridge can be created using the Webmin UI as follows :

Click on eth0 and change the IPv4 address to No address configured. Remember the current IP address and netmask, as they will be needed in the next step. Click the Save button.

Click Add a new bridge, and fill in the IP address and netmask that used to be assigned to eth0.

In the Connect bridge to interface field select eth0, then click Create.

Return to the main page of the Network Configuration module, and click on Routing and Gateways . Find the current default IPv4 gateway from the Active configuration tab, and enter it on the Boot time configuration tab with br0 selected as the interface.

Go back to the main page of the Network Configuration module, and click the Apply Configuration button.

Setting up a Fedora, CentOS or Redhat Host System

To setup a Redhat-based system to host KVM instances, the steps to follow are :

SSH in as root and install the KVM packages with the command yum install kvm qemu qemu-img parted

In the /etc/sysconfig/network-scripts directory, copy ifcfg-eth0 to ifcfg-br0.

Edit the new file and change the DEVICE line to DEVICE=br0.

In the same file, remove the HWADDR line, and change the TYPE line to TYPE=Bridge

Edit the ifcfg-eth0 file, and at the bottom add the line BRIDGE=br0

Apply the network settings with the command service network restart . This should be done at the console, as it will break network access to the host system if anything goes wrong.

Apply the network settings with the command /etc/init.d/networking restart or by rebooting . This should be done at the console, as it will break network access to the host system if anything goes wrong.